Pressure gun



June 23, 1964 .1. c. HOVELAND PRESSURE GUN Filed Feb. 15, 1961 INVENTOR JULIAN CLEON HWELAND United States Patent 3,138,303 PRESSURE GUN Julian Cleon Hoveland, North Surrey, British Columbia, Canada, assignor to M. D. Muttart, Edmonton, Alberta,

Canada Filed Feb. 13, 1961, Ser. No. 88,809 1 Claim. (Cl. 222-389) This invention relates to a pressure gun particularly for use in the application of mastic material in corners and cracks, but which may be used for any other desired purpose.

An object of the present invention is the provision of a pressure gun which holds a mastic or similar material to be discharged therefrom by fluid pressure, and which completely prevents the pressure fluid from getting into said material.

In the erection of houses and other buildings, what is known as a dry wall construction is commonly used. Instead of using wet plaster the inside walls are covered by plaster board which comes in large sheets. The cracks and joints between the sheets along the walls and in the corners are filled with a mastic material. Guns for directing the mastic into'these joints have been in use for some time. Such guns consist of a cylinder with a free piston therein which is moved by air under pressure against the mastic to force it out through a discharge nozzle. The prior guns were not entirely satisfactory since it was impossible to keep the pressure air from getting past the piston into the mastic with the result that when the air reached the nozzle, the mastic instead of flowing out evenly and under control, spurted out and spattered all over the wall. In other words, the guns were not reliable.

The present invention overcomes this problem by providing means at the piston for trapping any pressure fluid attempting to move past the piston towards the mastic, and means for directing the trapped fluid out of the gun. As a result, the mastic always flows under control evenly from the gun.

A pressure gun according to the present invention comprises a cylinder closed at the ends thereof, and having a discharge outlet at one end and a pressure fluid inlet at the opposite end. The pressure fluid is usually air, but it may be a liquid, such as water. A piston is slidably mounted in the cylinder and is movable towards the outlet by pressure fluid entering the cylinder through said inlet. This piston has a peripheral wall slidable over the cylinder surface, and, usually, sealing means of the type commonly used for such pistons. Passage means is provided in the piston and opens through and around the peripheral wall thereof, and hose means within the cylinder and communicating with the piston passage means opens out through said cylinder near its inlet end to bring the passage means into communication with the atmosphere outside the cylinder. With this arrangement, the pressure in the passage means is the same as the atmospheric pressure outside the gun so that any pressure fluid moving past the piston flows into the comparatively low pressure area, and travels along the hose means to the outside atmosphere.

The hose means is preferably in the form of a flexible hose, and an important feature of this pressure gun is means therein for maintaining the hose in spiral formation so that said hose does not interfere with the return of the piston when it is desired to refill the gun.

Two forms of the invention are illustrated in the accompanying drawings, in which,

FIGURE 1 is a longitudinal section through a preferred form of pressure gun,

FIGURE 2 is a cross section taken on the line 22 of FIGURE 1,

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FIGURE 3 is a cross section taken on the line 3--3 of FIGURE 1, and

FIGURE 4 is a fragmentary sectional view similar to FIGURE 1, illustrating an alternative form of a pressure gun.

Referring to FIGURES l and 3 of the drawings, 10 is a pressure gun including a cylinder 12 of any desired cross sectional shape, usually circular as shown. This cylinder has end walls 13 and 14 removably mounted therein. In this example end walls 13 and 14 fit within the cylinder ends and are removably retained therein respectively by screws 16 and 17. A discharge outlet in the form of a pipe 20 is provided at end wall 14, said pipe extending through and being carried by said wall. A nozzle 21 is connected to the outer end of pipe 20, and has a control valve 22 therein which is operated by means of a handle 23.

A pressure fluid inlet 26 is provided at the opposite end of cylinder 12, preferably in end wall 13 centrally thereof. A stiff tube 28 extends through inlet 26 and is carried by wall 13. This tube extends a short way into the cylinder, and has a plurality of apertures 29 therein. A flexible hose 32 extending from a suitable source of fluid under pressure is removably connected to the outer end of tube 28. The fluid for guns of this type is usually air, in which case, the hose extends from a compressor, pressure tank or air bottle.

A piston 35 is slidably mounted in cylinder 12 and has a peripheral wall 36 which is slidable over the inner surface 37 of said cylinder. Piston 35 is provided with standard sealing cups 39 and 40 on its opposite ends 41 and 42 slidably to engage cylinder wall 37. The piston divides the cylinder into a material chamber 46 and a pressure chamber 47, the respective'sizes of which vary during movement of the piston. Material chamber 46 is at the outlet 20 end of the cylinder, while pressure chamber 47 is at the inlet 26 end of said cylinder. Fluid under pressure entering chamber 47 from hose 32 moves piston 35 against material in chamber 46 to force said material through outlet 20 and nozzle 21 when valve 22 is open.

Passage means 50 is provided in piston 35 which opens through and around the peripheral wall 36 thereof. In this example, the passage means includes a groove 52 in wall 36 extending around the piston and opening out- Wardly therefrom, and at least one passage 53 extending inwardly from said groove towards the centre of the piston and opening out at 54 through the end 42 thereof. Although a groove is preferred, a plurality of holes may be provided instead of groove 52, said holes opening out from the peripheral wall 36.

Hose means is provided within cylinder 12 communicating with passage means 50 and opening out through the cylinder near the inlet end 13 thereof. This hose means is preferably in the form of a flexible hose 58 which is connected to the end 54 of passage 53 of piston 35. This hose is wound in a spiral, indicated at 60, and opens out through end wall 13 at 61. Although the hose 58 does not have to be wound in a spiral, it is preferably so Wound so that when piston 35 is moved towards end wall 13, the hose will not interfere with this action or be caught and perhaps damaged. Furthermore, it is highly desirable to provide means for maintaining hose 58 in its spiral formation. This is accomplished in a very simple manner by a stiff flexible wire 64 connected to and extending along the hose in a spiral. The simplest way to attain the desired results is to extend wire 64 through the hose as shown. When hose 58 and wire 64 are wound into spiral 60, they remain in that formation as a result of the stiifness of the wire. If desired, one end of wire '2 a; 64 may be anchored to prevent it from being displaced from the hose, as indicated at 66 in FIGURE 1.

Hose 58 keeps groove 52 and passage 53 of the passage means 50 of piston 35 in communication with the atmosphere outside cylinder 12. As fluid under pressure is directed by hose 32 into chamber 47 of the gun, the piston is moved against the material in chamber 46 to keep it under pressure. Thus, when valve 22 is opened, the material flows through nozzle 21. The fluid of chamber 47, usually air, attempts to move past piston 35 into chamber 46. However, groove 52 provides a comparatively low pressure area so that any such fluid, taking the path of least resistance, flows into the groove, along hose 58 and out of the gun. Therefore, the piston passage means and hose 58 prevents any of the pressure fluid from reaching chamber 46.

When chamber 46 is empty, piston 35 is moved back towards end wall 13 to enable the chamber to be filled again. The spiral formation of hose 58 prevents said hose from getting in the way or being damaged during this action. The stifl wire 64 ensures the hose remaining in its spiral configuration without interfering with the operation of the hose or the movement of piston 35.

FIGURE 4 illustrates an alternative pressure gun a in which the hose means is in the form of a telescopic tube 72 connected at 73 to the outer end of passage 53a of piston 35a. Telescopic tube 72 opens out at 75 through end wall 13a of cylinder 12a. Otherwise, gun 10a is constructed in the same manner as gun 10.

When gun 10a is in operation, it functions in the same way as gun 10, but as piston a is moved away from and towards cylinder end 13a, telescopic tube 72 respectively lengthens and shortens accordingly.

What I claim as my invention is:

In a pressure gun including a cylinder closed at its ends with a discharge outlet at one end and a fluid inlet at its opposite end and a piston having a peripheral wall and mounted slidably in the cylinder to be moved by a pressure fluid forced into the cylinder at the fluid inlet, a low pressure area in the piston opening out therefrom around the peripheral wall of the piston and spirally wound hose means positioned in the cylinder between the fluid inlet and the piston and connected to the low pressure area of the piston at its one end and opening out through the end of the cylinder near the fluid inlet to maintain the low pressure area of the piston in constant communication with the atmosphere outside the cylinder, such low pressure area being adapted to trap any pressure fluid moving past the piston and to direct such trapped fluid to the hose means.

References Cited in the file of this patent UNITED STATES PATENTS 2,811,950 Entz Nov. 5, 1957 2,918,903 Geyer Dec. 29, 1959 2,966,887 Arnold Jan. 3, 1961 3,074,437 Mercier Jan. 22, 1963 

